Orca
The killer whale (Orcinus orca), commonly referred to as the orca whale or orca, and less commonly as the blackfish, is a toothed whale belonging to the oceanic dolphin family. Killer whales are found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas. Killer whales as a species have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammals such as sea lions, seals, walruses and even large whales. Killer whales are regarded as apex predators, lacking natural predators. Killer whales are highly social; some populations are composed of matrilineal family groups which are the most stable of any animal species.[5] Their sophisticated hunting techniques and vocal behaviors, which are often specific to a particular group and passed across generations, have been described as manifestations of culture.[6] The IUCN currently assesses the orca's conservation status as data deficient because of the likelihood that two or more killer whale types are separate species. Some local populations are considered threatened or endangered due to prey depletion, habitat loss, pollution (by PCBs), capture for marine mammal parks, and conflicts with fisheries. In late 2005, the "southern resident" population of killer whales that inhabits British Columbia and Washington state waters were placed on the U.S. Endangered Species list. Wild killer whales are not considered a threat to humans,[7] although there have been cases of captives killing or injuring their handlers at marine theme parks. Killer whales feature strongly in the mythologies of indigenous cultures, with their reputation ranging from being the souls of humans to merciless killers. Description Killer whales distinctively bear a black back, white chest and sides, and a white patch above and behind the eye. Calves are born with a yellowish or orange tint, which fades to white. Killer whales have a heavy and robust body[38] with a large dorsal fin up to 2 metres (6.6 ft) tall. Behind the fin, they have a dark grey "saddle patch" across the back. Antarctic killer whales may have pale grey to nearly white backs. Adult killer whales are very distinctive and are not usually confused with any other sea creature.[39] When seen from a distance, juveniles can be confused with other cetacean species such as the false killer whale or Risso's dolphin.[citation needed] The killer whale's teeth are very strong and covered in enamel. Its jaws are a powerful gripping apparatus, as the upper teeth fall into the gaps between the lower teeth when the mouth is closed. The front teeth are inclined slightly forward and outward, thus allowing the killer whale to withstand powerful jerking movements from its prey while the middle and back teeth hold it firmly in place.[40] Killer whales are the largest extant members of the dolphin family. Males typically range from 6 to 8 metres (20–26 ft) long and weigh in excess of 6 tonnes (5.9 long tons; 6.6 short tons).[41] Females are smaller, generally ranging from 5 to 7 metres (16–23 ft) and weighing about 3 to 4 tonnes (3.0 to 3.9 long tons; 3.3 to 4.4 short tons).[41] The largest male killer whale on record was 9.8 metres (32 ft), weighing over 10 tonnes (9.8 long tons; 11 short tons), while the largest female was 8.5 metres (28 ft), weighing 7.5 tonnes (7.4 long tons; 8.3 short tons).[42] Calves at birth weigh about 180 kilograms (400 lb) and are about 2.4 metres (7.9 ft) long.[43][44] The killer whale's large size and strength make it among the fastest marine mammals, able to reach speeds in excess of 30 knots (56 km/h).[45] The skeleton of the killer whale is of the typical delphinid structure but is more robust in all respects.[46] The killer whale's integument, unlike that of most other dolphin species, is characterised by a well-developed dermal layer with a dense network of fascicles of collagen fibers.[47] Killer whale pectoral fins are large and rounded, resembling paddles. Males have significantly larger pectoral fins than females. At about 1.8 metres (5.9 ft) the male's dorsal fin is more than twice the size of the female's and is more of a triangular shape—a tall, elongated isosceles triangle—whereas hers is shorter and more curved.[48] Males and females also have different patterns of black and white skin in the genital area.[49] Sexual dimorphism is also apparent in the skull; adult males have a longer lower jaw than females, and have a larger occipital crest.[47] Individual killer whales can often be identified from the dorsal fin and saddle patch. Variations such as nicks, scratches, and tears on the dorsal fin and the pattern of white or grey in the saddle patch are unique. Published directories contain identifying photographs and names for hundreds of North Pacific animals. Photo identification has enabled the local population of killer whales to be counted each year rather than estimated and has enabled great insight into lifecycles and social structures.[50] White killer whales occur sporadically among normal killer whales, but are rare. They have been spotted in the northern Bering Sea and around St. Lawrence Island, and near the Russian coast.[citation needed] In February 2008, a white killer whale was photographed 2 miles (3.2 km) off Kanaga Volcano.[51][52] Killer whales have good eyesight above and below the water, excellent hearing, and a good sense of touch. They have exceptionally sophisticated echolocation abilities, detecting the location and characteristics of prey and other objects in their environment by emitting clicks and listening for echoes. Category:Animals Category:Mammals Category:World Wide Animals Category:Carnivores